4.2 Preliminary Design Concept Conference
The Preliminary Design Concept Conference (PDCC) is a meeting of key individuals used to evaluate and update the project scope and establish additional fundamental aspects of a project. The PDCC facilitates agreements on basic project features by concerned stakeholders and enhances relationships among those parties.
The PDCC is conducted prior to beginning preliminary engineering activities (i.e., preliminary design, environmental investigations, public involvement activities, ROW determination, and preliminary utility investigations).
Since a great deal of time can pass between the Planning/Programming and Preliminary Engineering phases, it is essential to revisit the project scoping information including data collection and site visit activities.
Preliminary design activities undertaken prior to the NEPA environmental clearance must not materially undermine consideration of project alternatives.
The PDCC decisions are documented in the DSR (see
) to help ensure that the project team does not overlook potentially critical issues and to ensure continuity of the project throughout development. The DSR constitutes an understanding of basic features of the project by FHWA, Divisions, Districts, Area Offices and LGs.
The PDCC includes attendees from all SME areas applicable to the project (e.g., area office, maintenance, roadway, bridge, drainage, traffic, construction, utilities, ROW, and environmental)
Outcomes from the PDCC Meeting include:
- Anticipated pavement structure options (consideration to resiliency for different climates);
- Baseline Oracle Primavera Cloud (OPC) schedule;
- Construction phasing/traffic handling;
- Design and construction schedules and consideration of accelerated construction techniques or contract provisions;
- Design criteria determination;
- Determination of additional data collection needs and responsible persons;
- Existing and future traffic volumes;
- Existing bridge data (i.e., condition assessments; bridge inspection reports; type, size and location; historical bridge data, etc.);
- Federal letter of authority for preliminary engineering;
- FHWA Cost and Schedule Risk Analysis (CSRA) – for major projects (see );
- Geometric design elements;
- Geotechnical data requirements;
- Hydraulic elements;
- Identification of multimodal needs (e.g., bicycle, pedestrian, transit, freight, etc.);
- Identification of needed agreements and permits;
- Identification of project stakeholders and needed coordination;
- Identification of roadway, bridge, drainage, traffic/safety, ADA pedestrian, bicycle, environmental and ROW/utility tasks to be performed;
- Key Dates / Special Events when roadway closures are prohibited;
- Maintenance concerns that may influence design;
- Potential ROW needed;
- Potential utility adjustments;
- Railroad impacts;
- Review of planning estimate, project programming and funding data;
- Status of environmental/public involvement process;
- Status of schematic completion;
- Surveying/photogrammetric requirements;
- Type of Geometric Schematic/Layout required;
- Updated project scoping documents (e.g., goals, objectives, constraints, and risks); and
- Value engineering analysis requirements (see ).
Scheduling the PDCC and facilitating the meeting should be accomplished by the TxDOT PM directly responsible for the design and development of the project. Suggested attendees are as follows:
- Area Office staff who will have design and/or construction responsibilities;
- Maintenance Supervisor who will be responsible for maintenance of the roadway;
- District design and review staff (i.e., roadway, bridge, drainage, traffic, landscape and railroad);
- Bicycle/pedestrian coordinator;
- Transit coordinator;
- District construction office staff;
- District survey staff;
- District environmental, ROW, and utility staff; and
- Local government staff directly involved with the project development or impacted by the completed project (i.e., funding responsibilities, review responsibilities, etc.).
All design decisions are documented in the DSR and can be reviewed by DES at the request of the PM.
4.2.1 Project Scoping Documents Review
Obtain and review the original project scoping documents from the DSR and the planning/programming estimate and schedule prepared during the planning and programming phases of project development. These initial documents serve as a baseline to guide the proposed preliminary engineering and final design of the project.
Project scoping documents to be reviewed and updated include:
- Project objectives and goals;
- Proposed project activities;
- Planning estimate;
- Letting year and milestone submittal dates;
- Environmental document type, concerns, constraints, and specific compliance requirements;
- ROW needs and utility conflicts;
- Railroad issues;
- Stakeholder log;
- Risk register; and
- Traffic and safety scoping form.
Changes or updates to the project scope are documented in the DSR.
Project schedules are expected to have an Original Baseline type for all state-let projects with an Estimated Let Date in TxC that is within the first four years of the 10-year UTP portfolio window and for any project that is actively being developed.
4.2.2 Design Criteria and Controls
The design criteria and controls to be used on the project are established and documented in the DSR at the beginning of project development. The design criteria to be used is determined by the type of construction that is proposed and other selection considerations including:
- Whether the project is on the Federal National Highway System (NHS), State Highway System, or off-system roadway;
- Whether the project is or needs access control (i.e., conventional or access-controlled facility);
- Functional classification of the roadway (i.e., freeway, arterial, collector, or local);
- Context classification of the roadway (i.e., rural, rural town, suburban, urban, or urban core);
- Terrain classification of the roadway (i.e., level, rolling, or mountainous);
- Traffic characteristics of the roadway (e.g., current/projected Average Daily Traffic (ADT), operations, safety); and
- Funding category of the project (certain funding categories pertain to specific design criteria).
gives definitions of the different highway construction categories.
Highway Construction Category | Definition |
Resurfacing | Limited existing pavement surface repairs such as milling, spot patching, seal coat, rut repair, crack sealing, and fog sealing. |
Restoration | Existing pavement structure repairs such as patching or rebuilding short sections of road, hot mix overlays, shoulder edge repairs, or minor safety improvements (i.e., guardfence, pipe headwalls, etc.). |
Rehabilitation | Partial or full depth pavement reconstruction on existing profile/alignment such as removal and replacement of the existing riding surface and base material, driveway improvements, ditch regrading or safety improvements (i.e., guardfence, pipe headwalls, etc.). If approved, minor lane/shoulder widening, adding medians/curbing, minor improved drainage design or intersection improvements are included. |
Reconstruction | Projects that utilize an existing roadway alignment (or make only minor changes to an existing alignment) but involve a change in the basic roadway type. Changes in the basic roadway type include widening a road to provide additional through lanes or adding a raised or depressed median where none currently exists, and where these changes cannot be accomplished within the existing roadway width (including shoulders). |
New Construction | Projects on a new alignment or new construction. |
Roadway Design Criteria | Highway Construction Categories | Definition |
2R | Resurfacing and Restoration |
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3R | Resurfacing, Restoration and Rehabilitation |
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4R | Resurfacing, Restoration, Rehabilitation, and Reconstruction and New Construction |
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5R | Mobility Corridors | Projects that are intended to regenerate, or produce new, long-term transportation opportunities including multiple modes such as rail, utilities, freight, and passenger characteristics. |
The appropriate design criteria for the construction type are chosen according to guidance found in the RDM based on the functional and context classification of the roadway. Refer to Chapters 1 – 12 of the RDM for more guidance on the selection of the applicable design criteria.
Design controls that are established according to the selected design standards include:
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Roadway Design Criteria | Definition | Reference | |
PM | Preventative Maintenance | Projects with work to preserve, rather than improve, the structural integrity of the pavement and/or structure. Includes ACP overlays (maximum 2” thick); seal coats; cleaning and sealing joints and cracks; patching concrete pavement; milling or bituminous level-up, shoulder repair; micro-surfacing; scour countermeasures; restoring drainage systems, cleaning and painting steel members to include application of other coatings, cleaning and sealing bridge joints, bridge deck protection, cleaning and resetting bearings, cleaning rebar/strand, and patching structural concrete. | Maintenance Management Manual and Maintenance Operations Manual |
5R | Mobility Corridors | Projects that are intended to regenerate, or produce new, long-term transportation opportunities including multiple modes such as rail, utilities, freight, and passenger characteristics. | Roadway Design Manual |
Special Facilities | Highway Safety Improvement Program (HSIP) | Projects involving highway safety improvements including medians, turn lanes, intersections, traffic signals, and rumble strips. Projects must align with the emphasis areas in the Texas Strategic Highway Safety Plan (SHSP) such as roadway and lane departures, intersections, older road users, and pedestrian safety. | Highway Safety Improvement Program Guidelines |
Off-System Bridge Replacement & Rehabilitation | Projects that are included in the off-system bridge replacement and rehabilitation program; the facility is not likely to be added to the designated state highway system; and has a current ADT of 400 or less. High-volume (current ADT > 400) off-system bridge replacement and rehabilitation projects should use the appropriate 3R or 4R criteria. | Roadway Design Manual | |
Historically Significant Bridges | Projects that contain a designated historically significant bridge. | Historic Bridge Manual | |
Texas Parks and Wildlife Department (TPWD) | Projects that include work on Park Roads (PR) and Wildlife Roads (PW). This includes constructing, repairing and maintaining roads in and adjacent to state parks, state fish hatcheries, state wildlife management areas and their support facilities. | Texas Parks and Wildlife Department Design Standards for Roads and Parking | |
4.2.3 Additional Data Collection
Prior to the PDCC, additional data may be needed for making engineering and environmental decisions related to project design. Data collection efforts must be as complete as possible so project solutions providing the most benefit are selected.
4.2.3.1 Right of Entry
ROE must be obtained in writing on a form that is legally binding before entering private property. ROE is permission granted by a landowner for others to enter the landowner's property for a specific purpose. Activities such as surveying and geotechnical and environmental studies should be coordinated and covered under one ROE if possible (landowners can be confused by multiple requests). Include all property in the ROE where work activities will be performed as well as property that will be traveled on to reach work sites.
Conditions may exist for entry onto railroad property. ROE requests to access railroad property must be processed through the District railroad coordinator or through the RRD - Rail Letting Section.
Property requiring entry should be identified and coordinated early – several rounds of ROE requests may be needed to obtain the needed permission. It may be advantageous to send ROE letters by certified mail to maintain documentation of receipt.
Pay close attention to instructions from the landowner on the ROE form (e.g., call before coming, close all gates, use a specific entrance location, etc.).
It is a best practice to contact the landowner a few days prior to crews being on the property as a courtesy and show of good faith.
If ROE cannot be acquired through standard means (e.g., ROE letters sent by certified mail, personal contact with property owners, etc.), a request for a court order can be provided to the ROW - Survey Section for review and processing. It is encouraged to avoid court orders if possible, in order to maintain good relations with the public.
An example of a ROE letter is given in the references below.
ROE can take several months to complete – include this activity in the project schedule.
4.2.3.2 Initial Survey Data
Survey data includes digital maps, terrain models, and orthophotography. The data may already exist (e.g., Google Maps, Nearmap, etc.) or, depending on project requirements, may need to be created. Geospatial data can be created using various technologies. Coordinate with District survey staff to determine the extent of available data.
The following methods are suggested for gathering geospatial data:
- Small areas, less than 10 acres:
- Land surveying using conventional optical or global positioning system (GPS) surveying equipment; or
- Static (terrestrial) Light Detection and Ranging (LiDAR).
- The following are more cost-effective for areas greater than 10 acres:
- Aerial photogrammetry;
- Airborne LiDAR;
- Close-range photogrammetry: terrestrial, mobile, or unmanned aircraft system (UAS); or
- Mobile LiDAR.
If the project is a Digital Delivery project, a higher level of survey data will be needed.
Coordinate survey requirements for a Digital Delivery project with the DES and ROWs.
A land surveying task is accomplished using either optical surveying equipment (e.g., a total station) or by GPS. Individual points on the ground are located by the surveyor. In the office, the surveyed point data is processed creating a planimetric map and digital terrain model (DTM).
The procedures in Static LiDAR surveying are like land surveying in that a surveying instrument is set up on a tripod at the project site. Rather than locate individual points on the ground, the LiDAR scanner collects thousands to millions of individual points creating a dense “cloud” of located points. In the office, data is extracted from the “point cloud” using specialized software.
Aerial photogrammetry
typically uses piloted aircraft equipped with a large-format metric mapping camera; however, UAS and small format cameras can also be used.UAS is a tool used to collect qualitative (i.e., visual) and quantitative (i.e., metric) data. The role of UAS is similar to other tools sued to collect these same types of data: GPS, LiDAR, RADAR, Sonar, optical surveying equipment, and close-range and vertical photogrammetry.
Airborne LiDAR
uses one or more scanners mounted on an aircraft. The aircraft can be rotary-wing, like a helicopter, or fixed-wing. The mapping data is extracted from the point cloud.Close-range photogrammetry
can be static with the camera held in a fixed position, mobile, or airborne. Three-dimensional data is extracted from the imagery to produce planimetric maps and DTM data.Mobile LiDAR
uses one or more scanners mounted on a moving vehicle in contact with the earth’s surface. The vehicle can be a car or truck operating on a roadway, a vehicle operating on a rail line, or even a boat. Mobile LiDAR systems produce dense point clouds from which data can be extracted.Planimetric mapping and DTM extraction are done using stereoscopic viewing equipment and specialized software.
Most mapping is done using a network of ground control points. These are points that have been precisely located on the ground using surveying equipment. The control points form a geospatial reference frame for the subsequent mapping task. Often the ground control points are “targeted” using a painted “X” or similar figure. The target allows easy identification of the ground control point in the point cloud or on the photograph. Targeting is typically done prior to data collection.
Aerial photography can be collected, but not controlled. In this case, the imagery is primarily used to give an overview of a proposed corridor project or other large study area. The imagery can roughly be georegistered but must not be used for precise mapping.
4.2.3.3 Traffic and Safety Analysis
Current and projected traffic data is a key element in highway design. Obtaining traffic data early can assist in defining the typical section. However, if a project is on a new location or the alternatives being considered present a major change to the network (e.g., new location or ramp changes), it is recommended to
request the proposed traffic projections after a preferred alternative is agreed upon
and geometric elements (i.e., ramp locations) are further developed. Traffic data that has been previously requested in the planning project development phase must be reviewed for applicability and additional data may need to be obtained.Traffic data is also used for other work including environmental studies and pavement design. Coordinate with the District environmental staff to determine what type of traffic data is needed for environmental tasks. Coordinate with District pavement/laboratory staff for traffic data needed for pavement design.
Preliminary engineering phase analysis is a medium-detail analysis applied to projects at a middle development stage. Per the HCM, preliminary engineering phase analyses are “conducted to support planning decisions related to roadway design concept and scope and when alternatives analyses are performed.”
Refer to the TSAP Manual for details on the data and tasks to complete for traffic and safety analysis procedures to complete during this phase.
4.2.3.4 Related Data, Plans, Studies, and Reports
Existing studies and reports can provide information that will assist in decision making and help avoid rework.
Consider the following sources for additional data, plans, studies and reports:
- “As-built” construction plans;
- Bridge condition assessments;
- Bridge inventory data;
- Crash analysis and safety data;
- Environmental studies and schematics for previous or adjacent projects;
- Existing ADA barriers (TAMES/TCAP Toolbox);
- Existing hydrologic/hydraulic reports;
- FEMA floodplain studies;
- Formal or informal studies addressing a specific issue;
- Green Ribbon Master Plans for urban corridors with populations greater than 100,000;
- Pavement analysis data from Pavement Management Information System (PMIS);
- Pedestrian and bicycle plans;
- Previously studied but suspended projects;
- Project history files;
- Relevant project information for adjoining or parallel routes;
- ROW maps;
- Studies conducted by other agencies or special districts (e.g., MPO, flood control district, and city and county planning studies/maps) related to the proposed project concept or having possible impacts on project design;
- Texas Reference Markers, GIS data for railroads, city limits, and public roads;
- Traffic signal studies/Streetlight Data;
- TxDOT Bicycle Tourism Trails Example Network; and
- United States Geological Survey (USGS) data.
4.2.3.5 Existing Utilities Information
Utility locations must be identified early in project development. Coordination with utility owners is required when existing utilities are present. Utility locations should be identified early so there is time to consider the impacts in alternative selection.
Document any observation of utility locater markers and signs during the site visit. Contacting Texas 811 will alert utility owners of pipelines, telecommunication cables and power line to mark their buried assets on the project site. Coordinate this activity with survey staff to have lines marked prior to the field topo survey.
Utilities that are carried by a locally owned bridge or that will be impacted by bridge construction require coordination between the utility owner and the bridge owner (if different than the utility owner) to remove the utility conflict prior to letting the project. Category 6 funding is not permitted to pay for relocating utilities.
Be aware of local utilities such as regional water authorities that may not be included in a Texas 811 alert.
Early coordination with these type of underground utility owners is critical to correctly identify potential conflicts.
4.2.3.6 Early Coordination with Stakeholders
Early coordination with resource and regulatory agencies and other stakeholders is vital in identifying concerns and opportunities for a proposed project. The project development process can be streamlined by proactively seeking out potential stakeholders not previously identified.
Opportunities may be identified to perform joint activities with a project planned by an outside agency (e.g., MPO or LG). Early coordination with regulatory agencies may identify required actions that could be time-consuming and require long lead times in the schedule.
It is important to understand the needs of each stakeholder (individuals and groups) and develop an engagement plan that is best suited to their needs. This activity is closely coordinated with District environmental staff as part of the public involvement process (see
).
It is critical that all stakeholder commitments from TxDOT be documented and carried out through design of the project.
4.2.4 Site Visit
Prior to the PDCC, it is desirable to perform a site visit to update the existing site conditions from the scoping meeting site visit with the applicable SMEs. See
for additional information on performing the site visit and needed ROE to be obtained prior to accessing any property outside of state ROW.
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